The seismic cone consists of an S15 piezocone below a tri-axial accelerometer array. The Seismic Cone Penetration Test (SCPT) is carried out like a normal CPT but paused at 1m intervals to perform a seismic test. By striking a nylon block anchored to the grounds surface, a seismic shear wave is generated. The use of nylon produces a cleaner waveform in comparison to striking a traditional steel beam. For greater accuracy and reduction of noise, multiple waveforms can be stacked at each depth. The accelerometers are more sensitive than conventional geophones and provide larger signal to noise ratios allowing for improved confidence in results and deeper testing.
The direct measurement of shear wave velocity through 1m intervals allows for the reporting of the small strain shear modulus and constrained modulus to a greater degree of confidence than deriving from other ground investigation (GI). As well as producing high quality data, the SCPT is a fast method of GI with typical production rates between 50-70m of testing per day. Lankelma engineers process seismic data to provide technical parameters in a matter of days making SCPT a much faster GI method than soil sampling and laboratory testing, as well as providing parameters of the insitu soil conditions.
Small strain shear modulus is essential for predicting ground surface motions from earthquakes, evaluating foundation performance for vibrating equipment, offshore structure behaviour during wave loading and for predicting deformations around excavations.